The present invention, in one aspect, relates to a radio-controlled timepiece, a method of obtaining date/time information, and a storage medium.
Conventionally, there are electronic watches (radio-controlled timepieces) that accurately maintain the date/time that the watch counts by receiving radio waves from a navigation satellite (positioning satellite) of GNSS (global navigation satellite system) and obtaining date/time information therefrom. Such a radio-controlled timepiece does not require manual operation by the user and can count date/time at various locations in the world and accurately maintain the displayed date/time.
However, in an electronic watch, the load involved in receiving satellite waves is significantly greater than the load involved in counting and displaying date/time. Dealing with the reception of satellite waves gives rise to the problem of increased battery size and other associated problems such as increase in the size and weight of the electronic watch. To address such problems, various types of technologies for reducing energy consumption have been developed so far.
One of such technologies for reducing energy consumption includes shortening the time required for receiving radio waves. Japanese Patent Application Laid-Open Publication No. 2009-36748 discloses a technology that receives a predefined portion of the signal including date/time information according to a signal format (navigation message) transmitted by the GPS satellites and that temporarily pauses reception while the GPS satellites are transmitting unnecessary information, for example.
In this process, to avoid misidentifying date/time, parity data for the data block that includes the predefined portion of the signal described above is obtained to ensure the integrity of the incoming data.
However, in adverse reception condition such as when the signal strength of the received radio waves is low, the watch can misidentify part of the incoming codes. In a case like this, on one hand, a situation in which imprecise date/time is obtained needs to be avoided. On the other hand, however, if the reception is continued until the watch verifies all of the obtained code sequences, the reception time becomes longer, which lowers the efficiency of obtaining the date/time information and increasing the consumption of unnecessary power.